When inspecting a silicon wafer (to be referred to hereafter as a “wafer”) used in semiconductor manufacture, a surface inspection for detecting defects on the wafer surface is highly important and is therefore performed with a great deal of care to ensure a zero rejection rate. However, defects in the interior of the wafer have not been accorded much consideration in the prior art.
When a wafer is manufactured, defects (cracks, pinholes, or air bubbles) of several tens to several hundred μm existing in an ingot may be left on the surface or in the interior of the wafer during slicing. When these defects appear on the surface, they can be detected using a surface defect inspection device, but when the defects are left in the interior of the wafer, they cannot be detected by a defect inspection device for performing surface inspections.
Defects such as cracks, pinholes and air bubbles existing in the wafer interior may affect the performance of a semiconductor device, and therefore demand exists for a transmission inspection with which defects in the interior of a wafer can be detected.